How to build this for Ubuntu 16.04

The easiest way would be to download the .deb packages for zesty and installing them manually. (Note, that this fails in case that there are unmet dependencies.)

For building packages from source see http://packaging.ubuntu.com/html/packaging-new-software.html especially chapter 6.

Thanks Manfred. This is what I have done in my test environment, following your advice as far as I am able. The new file /etc/default/opendmarc was not installed even though I requested that it should be, it seems to have disappeared - is this a bug? I moved back my old settings (from /etc/default/opendmarc.dpkg-old) and all seems to work ok.

# have opendmarc 1.3.1 already installed and working - check version
sudo opendmarc -V
# now stop it
sudo systemctl stop opendmarc
# get the new files required for 1.3.2
cd /var/cache/apt/archives
sudo wget http://mirrors.kernel.org/ubuntu/pool/universe/libs/libspf2/libspf2-2_1.2.10-7build1_amd64.deb
sudo wget http://mirrors.kernel.org/ubuntu/pool/universe/o/opendmarc/libopendmarc2_1.3.2~Beta1-2_amd64.deb
sudo wget http://mirrors.kernel.org/ubuntu/pool/universe/o/opendmarc/opendmarc_1.3.2~Beta1-2_amd64.deb
# install them
sudo dpkg -i libspf2-2_1.2.10-7build1_amd64.deb
sudo dpkg -i libopendmarc2_1.3.2~Beta1-2_amd64.deb
sudo dpkg -i opendmarc_1.3.2~Beta1-2_amd64.deb
# be careful to look at and save the new settings for /etc/default/opendmarc manually - they don't get installed correctly
# - your old settings will be at /etc/default/opendmarc.dpkg.old
# check new installation
sudo opendmarc -V
sudo ps -AF|grep opendmar[c]
sudo systemctl status opendmarc

If there is something wrong with creation of the /etc/default/opendmarc config file during installation, then you might consider creating a bug report about that problem, but you should verify if that problem occurs also with a standard installation and not only when manually installing a version for a different Ubuntu release.

Is the program now working as desired, or do you see further problems?

Thanks Manfred. I have now verified that this problem also occurs when installing as normal (using apt-get install) in a standard Zesty installation. I will file a bug report.